100 million years old .. Excavations of old snakes with legs

Snakes with their smooth bodies and diversity of colors have amazed humans for a long time, but we know little about the evolutionary past of these legless lizards, due to the scarcity of excavations left by the ancestors of snakes that inhabited the earth with dinosaurs.

Legged chisels
As the writer Becky Ferreira says in her New York Times report on November 20, 2019, this is why snake lovers of recently excavated snake fossils in Argentina are considered important, as these complex fossils - Most of them are skulls - nearly 100 million years ago.

It also belongs to the extinct snake group "Najash", which still retains its hind legs. Fossils indicate that snakes lost their front legs much earlier than previously thought, but kept their hind legs for millions of years.

The discovery will also help solve puzzles about the period when snakes began to transform into their modern form.

The most exciting specimens
The author noted that Fernando Garberoglio, who led the research, discovered the most exciting new skull specimens in 2013 as a university student.

"This skull is now the most complete skull of a famous medieval snake and retains key data on the structure of ancient snakes," said Garberoglio, who is seeking a doctorate.

The exceptional conservation situation in which these fossils found Garberoglio and his colleagues enabled the study of ancient puzzles about the development of snakes, similar to the sequence of events that led to the lack of limbs.

The team examined the fossils using microscopic tomography (CT) scanning, an imaging technique that allows accurate details of the fossils to be studied without damaging them.

Scientists have not found fossils of the ancestors of the four-legged snake family, although they are certain they are, the writer said.

The new study suggests that these mysterious primary snakes may have lost limbs early in the process of snake development, at least 170 million years ago, but the back legs were suspended for tens of millions of years.

This means that rear-legged snakes, like the Nagash group, did not go through a short-lived evolutionary phase. Instead, the snakes that held two legs served as a sufficiently successful body structure for eons, until most snakes turned into snakes without limbs during the latter half of the Cretaceous.

Skulls solve the puzzle
"The study of snakes is really old, so there may not be any four-legged snakes like all the other lizards," says Michael Caldwell, a vertebrate paleontologist at the University of Alberta.

"Snakes were probably the first lizards to have had no limbs, but what was really interesting was that they also showed very clearly the characteristics of their skulls, a characteristic that characterizes them," Caldwell said.

According to the new study, a three-dimensional skull could solve the debate among scientists over the advantage of snake skeleton in early times.

Snakes currently lack the zygomatic bone, which is similar to cheekbones. However, it is unclear whether ancient snakes possess this cranial advantage. This discovery suggests that unlike the smaller mouths of modern snakes, their primitive ancestors had larger mouths.

"The absence of zygomatic bone in snakes is a common feature of all snakes and fossils," said Garberoglio.